Steel grit dryer

ABSTRACT

A mobile steel grit dryer used to dry steel grit may be configured with a number of different functions and features to assist a contractor in performing steel or other structure maintenance when using steel grit in resurfacing the structure. The steel grit dryer may be configured with a heat process vacuum bypass so that an off-board vacuum, such as a vacuum on a grit recycling system, may be utilized as opposed to having an onboard vacuum. The dryer may include multiple modes so that an operator may use different modes for different environmental conditions. An exoframe may provide for better durability when being transported to different jobsites. A variety of automation and safety features may also be provided to simplify and improve safety for operators.

RELATED APPLICATIONS

This application claims priority to co-pending U.S. Provisional PatentApplication Ser. No. 62/775,578 filed Dec. 5, 2018; the contents ofwhich are incorporated herein in their entirety.

BACKGROUND

The process of using grit, especially steel grit, as a blast media forcleaning steel goes back to the early 1900's, but it was not until themid-1980's that steel grit began to be used in mobile applications. Someof the first places steel grit was used was for blast cleaning of steeltanks of all types and sizes, including nuclear torus vessels, water,and fuel tanks. When used inside a tank, moisture was typically not aproblem, as the tank itself provided protection from rain and otherprecipitation.

The use of steel grit was so effective that contractors began using thesteel grit to blast the exteriors of tanks and then bridges. However,the exposure to the environment made contamination from suddenrainstorms and other water sources a problem. Steel grit by its naturerequires absolutely dry conditions (e.g., less than about 0.1%, lessthan about 0.05%, less than 0.001%, or lower), including the use ofcompressed air dried to a −10 degree dew point for abrasive blastingoperations as condensate tends to cause corrosion of the steel gritparticles.

When moisture comes in contact with steel grit particles, the moisturecauses the particles, which are generally the size of a grain of sand,to stick together until exposure to air begins the process of corrosion,which leads to rusting of the steel grit. When rusting occurs, the smallsteel grit particles are bonded together by the corrosion process as thegrit dries and rust forms. The corrosion process causes clumping in thesteel grit as the steel grit particles literally rust themselvestogether, forming irregularly shaped “rocks” of thousands of corrodedparticles. These rocks and corroded steel grit result in a damaged steelgrit that has to be thrown away or significantly reduces theeffectiveness of the steel grit in blasting structures. Moreover, wetsteel grit significantly negatively impacts steel grit recyclingoperations. For at least these reasons, operators typically avoid usingsteel grit in precipitation (e.g., rain or high humidity conditions),which is costly and inefficient.

The Economics of Using Steel Grit

In the process of abrasive blasting of bridges, tanks, ships and othersteel objects, steel grit is becoming a popular media for a number ofreasons. The primary reason is economics. The steel grit particles canbe recycled up to 50 or more times with non-metallic particles beingremoved on each pass through the recycling machine. In addition to therecycling benefit, the density of steel grit is roughly 2.5 timesgreater than sand or coal slag, so the impact of the steel grit on asteel member or other structural surface is greater, meaning that morework is accomplished each time a steel grit particle hits the surface.

Abrasive blasting systems are used in preparing surfaces for painting.Some abrasive blasting systems are configured to recycle blast mediaafter blasting the steel grit. The blast media capable of being recycledincludes garnet, specular hematite, steel grit, steel shot, and othermedias. The blast media is often cleaned at a certain stage in therecycling process to remove dust from the media, as the blast media isgenerally ineffective below a certain size (e.g., 15 mesh for steelgrit), as understood in the art. Cleaning the blast media typicallyincludes passing air across the blast media, so that as the blast mediais collected in a hopper, the dust is already removed from the blastmedia, thereby making the blast media ready for use in blasting againsta surface.

The steel grit abrasive blasting process is especially popular wherehazardous paint coatings are to be removed, which creates a quantity ofwaste that is then disposed of as hazardous waste by law. By using steelgrit, which gets recycled each time with all non-metallic hazardousmaterial being removed through the recycling machine, the volume ofwaste can be reduced to roughly 1% of what would be created ifnon-recyclable medias like sand or coal slag are used. The recyclingdramatically reduces the volume of waste that needs to be disposed of,thereby significantly reducing the cost of proper hazardous wastedisposal. These economic benefits are what justifies the cost of steelgrit recycling machines despite the drawbacks from precipitation, aspreviously described.

Because the cost of steel grit per ton is many times that of sand orslag, the steel grit may be recycled again and again to gain theeconomic benefits for the user, while at the same time reducing thevolume of waste taken to disposal sites. Thus, when the grit falls tothe containment surface or ground, the grit should be quickly recovered,usually using a vacuum device that pulls the grit back to the recyclingmachine.

Vacuuming or Gravity Recovery of Steel Grit

It is common today to use powerful vacuums driven by large dieselengines to recover the steel grit, whether the steel grit is collectedon the ground, on a containment surface, or into some sort of collectionhopper. In the recovery process, the steel grit can become mixed withflowing water from rain, which turns the mixture into damp or wet steelgrit, thereby making it even heavier than the normal density of 265 lbsper cubic foot. The added moisture additionally causes the steel grit tobecome sticky, where the granular steel grit no longer flows as it wouldat an angle of repose of between approximately 30 and 40 degrees.

Because the steel grit is so valuable, costing up to $900/ton or more,the operator recovers the grit back to the recycling machine even thoughit is known that the free moisture will cause clogging and eventualclumping as the grit turns rusts. While vacuuming the steel grit forrecycling, large water droplets are typically removed from the steelgrit. However, enough moisture content on the grit itself remains tocause the rusting and clumping processes. In the process of vacuuming,any opening or wear of the vacuum hose can also allow water to enter thesystem, thereby causing further moisture problems.

If the wet grit is allowed to sit for a prolonged period of time (e.g.,a few days), the grit can become so hard that it typically has to beremoved using a jack hammer or other impact device. When sitting in ahopper, the water naturally drains to the bottom and can be drained offif a stainless steel filter screen at the bottom allows for drainage.However, moisture content residing on the surface of the steel grit thatis not removed during the vacuuming process typically remains longenough to cause the rusting and clumping processes to occur.

SUMMARY

To help reduce or avoid rusting and clumping processes of steel grit tooccur, a drying process of the steel grit may be performed. In oneembodiment, the drying process may occur prior to recycling the steelgrit through a blasting recycling system. The drying process may includea pre-classification process to remove rocks and other large debris fromthe steel grit at the steel grit blasting site. As described herein, thedrying process may be performed separately from the recycling process inthat the steel grit dryer may be a separate machine from the blastmachine, but use a vacuum from the blast machine in transporting thesteel grit to the grit dryer and then from the grit dryer to the blastmachine. Both the grit dryer and blast machine may be mobile.Alternatively, one or both of the machines may be stationary (e.g., notpositioned on a trailer with wheels, but rather being positioned on askid or other base member).

The drying process may be performed in a variety of different ways. Onetechnique may utilize a rotary drum that allows for the steel grit to berotated and dropped using gravitational forces through heated air. Theheated air may be drawn through the rotary drum using an exhaust fanthat causes a slight negative pressure or pulled air within the rotarydrum. The air may be heated in a variety of different ways, includingusing a flame that directly or indirectly heats air in the drum. Othernon-flame techniques for heating the air may alternatively be utilized.

Humidity sensor(s) and/or temperature sensor(s) may be used incombination with a processing system to monitor moisture content on thegrit indirectly by monitoring the moisture or temperature in the air,such as the heated air in the rotary drum, in which the grit is beingrecycled. Temperature sensors (e.g., infrared (IR) sensors) or othersensors may be utilized to indirectly determine moisture contained onthe steel grit. The processing system may use sensor measurements tocontrol speed of the rotary drum, angle of the rotary drum, time inwhich the grit is exposed to the heated air, temperature of the air,pressure of the air, speed of the heated air, and other parameters thataffect the drying process. In addition, if the processing systemdetermines that a moisture level or temperature of the air crosses athreshold level (i.e., either a high or low threshold level), then theprocessing system may alter the operation of a drying module that isperforming the drying process. If, for example, the moisture level dropsbelow a threshold level that is indicative that substantially nomoisture exists, then the processing unit may redirect the grit to avoidthe drying module and turn off the drying module to save power. Forexample, if the temperature of the air and/or steel grit is above acertain threshold, that, too, may be indicative of the moisture on thesteel grit being below a certain percentage. If, for example, themoisture level increases, the processing unit may route the grit to thedrying module and establish or alter parameter(s) to increase ordecrease drying power of the grit dryer or drying module, which is anintegrated, steel grit dryer onboard a steel grit recycling machine thatmay or may not include a steel grit blasting module. A notification toan operator in the form of an audible and/or visible signal may begenerated when switching grit being routed to and from the grit dryermodule.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the present invention are described indetail below with reference to the attached drawing figures, which areincorporated by reference herein and wherein:

FIG. 1 is an illustration of an illustrative bridge on which steel gritis used to blast steel surfaces in preparation for painting;

FIG. 2 is an illustration of an illustrative dry dock including a marinevessel that is being maintained, including being resurfaced andrepainted so as to limit environmental damage (e.g., corrosion from saltwater) to the steel hull;

FIG. 3 is an illustration of an illustrative abrasive blasting machinein accordance with the principles provided herein;

FIGS. 4A and 4B (collectively FIG. 4) are block diagrams of illustrativesteel grit dryer components and (a) steel grit and airflow paths and (b)electrical components of an inline steel grit dryer with respect to avacuum hose and a steel grit recycling machine, for example, to whichdried steel grit is conveyed from the steel grit dryer;

FIGS. 5A-5K are illustrations of an illustrative steel grit dryer thatutilize the principles of operation;

FIGS. 6A and 6B are illustrations of an illustrative pre-classifierconfigured as a double drum trommel;

FIGS. 7A-7C are illustrations of an illustrative pre-classifier, such asthe double drum trommel of FIG. 6, that utilizes one or more load cellsto weigh steel grit within the pre-classifier;

FIG. 8 is a flow diagram of an illustrative process for measuring weightof steel grit within a pre-classifier of a mobile steel grit dryer;

FIG. 9 is an illustration of a scene in which a truck may be connectedto a mobile steel grit dryer to pull the mobile steel grit dryer to ajobsite, for example;

FIGS. 10A-10C are illustrations at different angles and zoom levels of asteel grit dryer, respectively, of a rotating drum in which steel gritmay be dried is fixedly directly or indirectly secured to a structure,such an exoframe, at which the rotating drum is positioned;

FIG. 11, a flow diagram of an illustrative process for drying steelgrit;

FIG. 12 is a flow diagram of an illustrative process of operating amodulating valve for use controlling temperature used to dry steel grit;

FIG. 13 is a flow diagram for a process for operating a steel grit dryerin different modes;

FIG. 14 is a flow diagram of an illustrative process for pre-classifyingsteel grit;

FIG. 15 is a flow diagram of an illustrative process for manufacturing amobile steel grit dryer with an exoframe;

FIG. 16 is a flow diagram of an illustrative process for performing anangle sense interlock;

FIGS. 17A and 17B are illustrations of an illustrative wearable devicethat an operator may use when operating the steel grit dryer to receiveinformation and optionally control certain aspects of the steel gritdryer; and

FIG. 18 is an illustration of an illustrative grit moisture measurementtool that may be used to measure moisture of the grit, such as steelgrit, to aid an operator in determining when to use the steel gritdryer.

DETAILED DESCRIPTION OF THE DRAWINGS

Steel Grit Blasting and Recycling Processes

The use of steel grit in preparing surfaces for repainting is the mosteffective and efficient way to clean a steel surface as a result of thesteel grit being significantly heavier than other abrasives and havingthe ability to be recycled upwards of 100 to 200 times. Many otherabrasives, such as sand and coal slag, are relatively light in weight ascompared to steel grit and cannot be recycled, so those types ofabrasives are the least effective and least efficient. In addition tothe recycling benefit, the density of steel grit is roughly 2.5 timesgreater than sand or coal slag, so the impact of the steel grit on asteel structure is greater, meaning that more work is accomplished eachtime a particle hits the surface of the steel structure. A fewabrasives, such as garnet grit, can be recycled, but limited to betweenfive and eight times as a result of the garnet grit essentially wearingout and becoming too small to be an effective abrasive. Hence, steelgrit is critically important to contractors who are in the business ofrepainting large steel structures, such as bridges and marine vessels.As a result of the steel grit having the ability to be recycled so manytimes, it is 99% or higher more efficient than other single-useabrasives and 95% more efficient than other abrasives that can berecycled a limited number of times. And, because of the weight of thesteel grit, the efficiency for resurfacing steel structures may be ashigh as 20% or more for the contractors (e.g., 20% or more resurfacingcan be accomplished in the same period of time as compared to the use oflighter abrasives).

Although steel grit is so much more effective and efficient, one problemthat exists is that the steel grit clumps and corrodes whenprecipitation comes in contact with the steel grit, which causes thesteel grit to become oxidized when further exposed to air. A steel gritdryer may be used to dry the steel grit so as to reduce or eliminate theoxidation process, thus reducing or preventing the steel grit fromrusting. The steel grit dryer is meant to essentially evaporate moisturecontent from the steel grit as the steel grit is being recycled. Even inthe case of using stainless steel grit, which is more expensive thanconventional steel grit, not corroding due to moisture, the moisturecauses the stainless steel grit to clump and stick together, therebycausing processing problems within steel grit recycling and/or blastmachines.

As understood in the art, steel grit blast machines are used to blastthe steel grit into the steel structures at high velocities. The steelgrit may then be collected, typically by a vacuum process for largerprojects, for reuse. If the steel grit contacts moisture, whether actualwater or due to being within a high humidity environment, moisturecontent ends up on the surface of the steel grit. To collect and recyclethe steel grit after blasting, a vacuum is often used by an operator.Larger recycling steel grit machines typically have onboard vacuums.Smaller blast-only machines generally do not have an onboard vacuum. Inthe case of a larger steel grit recycling machine, the vacuumed steelgrit is initially pre-classified to remove large debris (e.g., shoes,dead birds, nails, gloves, rocks, sticks, etc.), classified (e.g., steelgrit separated from other particulate matter, such as paint chips), andstored in a hopper or other container so that the steel grit is readyfor blasting again. Conventional pre-classifiers are typically formed ofplates defined defining screens to allow the steel grit to pass throughand prevent larger debris from passing through and fall into a bin forlater discarding. The debris and particulate matter may thereafter betransported to a hazardous waste removal location.

In particular, the steel grit abrasive blasting process is especiallypopular where hazardous paint coatings must be removed, which creates aquantity of waste that must then be disposed of as hazardous waste bylaw. By using steel grit, which gets recycled each time with allnon-metallic hazardous material being removed through the recyclingmachine, the volume of waste can be reduced to roughly 1% of what wouldbe created if non-recyclable medias, such as sand or coal slag, areused. The recycling of steel grit dramatically reduces the volume ofwaste that needs to be disposed because all other blast media isdisposed of as hazardous waste, thereby significantly reducing the costof proper hazardous waste disposal. These illustrative economicbenefits, which may be millions of dollars annually depending on thesize of the structure being resurfaced using steel grit, are whatjustifies the cost of steel grit recycling machines. Other economicbenefits, such as reducing wages and overhead by being able to work moreefficiently by using steel grit, further justify the use of steel gritas a blast media.

To avoid moist steel grit from slowing down the recycling process astypically occurs using existing recycling equipment that does notinclude the use of a steel grit dryer, a steel grit dryer may be used todry the steel grit prior to recycling. Specific steel grit dryerconfigurations and processes may be utilized to ensure that the steelgrit is efficiently collected, cleaned, dried, and delivered to a steelgrit recycling and blast machine. And, depending on the environmentalconditions (e.g., precipitation, humidity level, temperature, etc.), thesteel grit dryer may have different modes of operation so as to minimizefuel consumption and maximize speed of processing. For example, if theenvironment in which the steel grit is being used is rainy, then thesteel grit dryer may operate in a normal mode, such as at a temperatureand speed that is capable of drying the steel grit. If, however, theenvironment has no rain, but the humidity is high, then the steel gritdryer may operate at the same temperature to dry the steel grit, but ata faster speed since the steel grit is not as wet so as to moreefficiently dry and recycle the steel grit. If the environment has norain and low humidity, the steel grit dryer may not heat the steel grit,but process the steel grit to aid in removing dust from the steel grit.Other configurations and/or modes are possible for processing the steelgrit in the steel grit dryer, as described herein.

Steel Structures

With regard to FIG. 1, an illustration of an illustrative bridge 100 onwhich steel grit is used to blast steel surfaces in preparation forpainting is shown. The bridge 100 is near a coastline and extends overwater. Hence, the environment is often humid, which generally means thatmoisture content exists and steel grit that is used for resurfacing thesteel of the bridge 100 becomes corroded and may have a more limitedlifespan than what is possible for steel grit. Although containmentsystems are used to try and prevent rain and other precipitation fromimpacting the work areas for the resurfacing and repainting operations,it is not possible to keep all water away from steel grit that isblasted by a steel grit recycling machine that includes a blastingfunction on the surfaces of the bridge 100 that falls to the ground orscaffolding platforms as containment systems leak and water inevitablyenters into the containment area. With a steel grit dryer, moisturecontent may be removed from the steel grit during recycling such thatthe steel grit is protected from corrosion and flows better within therecycling machine and use of the steel grit is generally moreconsistent.

With regard to FIG. 2, an illustration of an illustrative dry dock 200including a marine vessel 202 that is being maintained, including beingresurfaced and repainted so as to limit environmental damage, such asthe steel hull being corroded by salt water, is shown. Because dry docksare in marine environments, salt water or rain water is often present.High humidity also plagues the dry docks due to being on a coastlinesuch that operators that resurface and repaint the surfaces of themarine vessel often avoid the use of steel grit because the cost of thesteel grit can be excessive with the losses due to moisture. Otherstructures, such as fluid tanks, offshore drilling rigs, buildings,dams, and so on, often have the same problems depending on the locationsand/or seasons. Hence, to improve the efficiency and reduce cost forcontractors to resurface steel structures, such as bridges and marinevessels, a steel grit dryer with certain features and functions may beused to aid in the recycling process of the steel grit.

Inline Steel Grit Dryer with Heat Process Bypass Vacuum Path

In the process of drying grit particles in a steel grit dyer, whetherportable or stationary, where dry, damp or wet grit is being recovered,the grit dryer separates internal processing components under a highvacuum from internal processing components not under vacuum. Theconfiguration of the steel grit dryer may be configured to bepneumatically positioned in line with (i) a vacuum hose used by anoperator to vacuum in steel grit and (ii) a vacuum typically positionedon a steel grit recycling machine. As will be shown in FIG. 4A, aprimary dryer component that is not under vacuum is a dryer, which mayinclude a rotary drum dryer. A separate airflow with heated air is runthrough the dryer from end-to-end and used to dry the granular steelgrit that has been moved to and loaded into the dryer for thermalprocessing (e.g., rotary thermal processing).

To apply the vacuum pressure airflow, a number of scenarios are possiblewith regard to configuring an inline grit dryer, including, but notlimited to:

(a) a portable (trailer or skid) or stationary grit recycling machinewith onboard self-contained vacuum is combined with an onboard,self-contained rotary grit dryer;

(b) a portable (trailer or skid) or stationary grit recycling machinewithout onboard self-contained vacuum is combined with an onboardself-contained rotary grit dryer, where vacuum is supplied by a separatefreestanding vacuum system;

(c) a portable (trailer or skid) or stationary grit recycling machinewith onboard self-contained vacuum is combined with a freestandingrotary grit dryer (see, for example, FIG. 3)

(d) a portable (trailer or skid) or stationary grit recycling machinewithout onboard self-contained vacuum is combined with a freestandingrotary grit dryer.

In each case, and as a restatement, recovery of dry, damp, or wet steelgrit is made possible by placing the portable or stationary grit dryer“inline” on the vacuum recovery hose path between where grit is pickedup (i.e., on the ground or platform beneath a structure at which thesteel grit has been blasted) to where the steel grit is vacuumed to,typically a steel grit recycling machine for large structures or astorage hopper for either large or small structures.

To accomplish the inline grit dryer configuration, a vacuum path, whichis typically formed by a hose, is broken or separated by inserting thegrit drying process in the middle of the grit flow from pickup (i.e.,vacuum hose handled by an operator) to the grit recycling machine, asfurther provided at least in FIGS. 3 and 4.

Steel Grit Recycling Machine and Steel Grit Dryer

With regard to FIG. 3, an illustration of an illustrative abrasiveblasting machine 300 in accordance with the principles provided hereinis shown. The abrasive blasting machine 300 in this configuration ismobile in that the machine 300 resides on a trailer 302 that enables theabrasive blasting machine 300 to be transported from job site to jobsite for performing abrasive blasting on a structure (e.g., bridge) atthe job site.

The abrasive blasting machine 300 is a series of complex systems thatare configured in a deliberate way to perform certain functions in acertain order. From front to rear, the abrasive blasting machine 300includes a compressor manifold 304 that enables multiple compressors tofeed into the manifold 304 for use in blowing blast media by theabrasive blasting machine 300. An engine 306, which may be a dieselengine or other powered engine, for use in producing vacuum power andgenerating hydraulic power for driving various components on theabrasive blasting machine 300. A vacuum 308 may be utilized to enable anoperator of the abrasive blasting machine 300 to vacuum blast mediaafter the blast media is projected onto surfaces of a structure beingprepared for a protective coating to be applied thereto. The abrasiveblasting machine 300 includes a number of modules, including apre-classifier 310 may be utilized to sort out debris or other materialthat is collected by the vacuum and greater than a certain size, such asthree-sixteenths of an inch, and an air wash 312 that is used to cleansedust that is collected by the vacuum 308. A classifier module 314, whichseparates steel grit from smaller debris, such as paint chips, sand, anddust, by using a magnetic drum, for example, that are collected by thevacuum process.

A storage hopper 316 may be utilized to store blast media that isutilized for performing the abrasive blasting by the abrasive blastingmachine 300. One or more pressure vessels 318 may be utilized togenerate a pressure for the blast media in being introduced into airflowcreated by a compressor. The pressure vessel(s) 318 may be in fluidcommunication with metering valves 320 that are selectively open andshut for introducing the blast media into airflow produced by thecompressor for use in blowing the blast media onto surfaces of astructure being prepared for a protective coating to be applied thereto.

In operation, airflow without blast media may be created and used by anoperator of a blast hose (not shown) that includes a nozzle (not shown).Blast media may be selectively added to the airflow and directed ontosurfaces of a structure. As understood in the art, the nozzle of a blasthose may include a “dead-man” switch (not shown) that, when in a firstposition, causes compressed airflow to be pushed through the blast hoseand nozzle, and, when in a second position, causes both airflow andblast media to be pushed through the blast hose and nozzle. The dead-manswitch may be in communication with a controller 322 and/or other valvecontrol circuitry (not shown) that causes the airflow and/or blast mediato be blown through the blast hose and nozzle. Alternative controlswitches may be utilized to control operation of the steel grit abrasiveblasting machine 300.

The controller 322 may be part of the abrasive blasting machine 300 andused to control components of the abrasive blasting machine 300. Thecontroller 322 may further be configured to collect and process sensordata from sensors that are applied to sense operation of variouscomponents of the abrasive blasting machine 300. The controller 122,which is fundamentally a processing unit that performs control and datacollection functionality, may be composed of one or more computerprocessors and other circuitry. The controller 322 may be utilized in amanner that generates “intelligence” for other machines, such as a steelgrit dryer, owners/operators of the machine 300, and customers of theabrasive blasting machine 300. In an embodiment, the controller 322 maybe configured to control and/or communicate commands and data with anonboard grit dryer module or standalone steel grit dryer for use indrying the steel grit.

To remove moisture content from the steel grit, or any grit material forthat matter, a steel grit dryer machine 324 (“steel grit dryer” or“dryer”) may be set inline with a vacuum path extending in fluidcommunication with the vacuum 308 of the abrasive blasting machine 300or an external, standalone vacuum (not shown). The vacuum path mayinclude a first vacuum hose 326 extending between the abrasive blastingmachine 300, heat bypass vacuum path in the dryer 324, and second vacuumhose 328 extending from the steel grit dryer 324 for use by an operatorto vacuum steel grit that has been used to blast a structure. The firstvacuum hose 326 may connect between a first connector 330 on theblasting machine 300 and a second connector 332 on the dryer 324. Theheat process vacuum bypass path in the dryer 324 allows for the steelgrit that is vacuumed into the steel grit dryer 324 and processedthereby without pulling heat from the dryer 324 into the steel gritblasting machine 300.

As described further herein, the steel grit is (i) removed from thevacuum pressure airflow path in the dryer 324, (ii) pre-classified undervacuum pressure, (iii) transitioned from the vacuum pressure to ambientpressure, (iv) dried by being exposed to heated air, and (v)re-entrained back into the vacuum pressure airflow path so that thedried steel grit can be flowed into the blasting machine 300. The heatprocess vacuum bypass path is isolated from heated air produced by aheat source, and may be used to pneumatically transport the dried steelgrit between the steel grit dryer 324 and the steel grit blastingmachine 300. The heat process bypass configuration of the vacuum pathallows for contractors to use an existing vacuum already available onthe abrasive blasting machine 300, thereby saving space and/or cost forthe contractor from having to operate a separate vacuum. The heatprocess bypass configuration further saves a manufacturer of the dryer324 from having to integrate a vacuum on the dryer 324, thereby savingcost from having to add a vacuum and space on the dryer 324.

Steel Grit and Airflow Paths

With regard to FIGS. 4A and 4B, block diagrams of illustrative steelgrit dryer components and (a) steel grit and airflow paths and (b)electrical components of an inline steel grit dryer 400 a and 400 b(collectively 400) with respect to a vacuum hose 402 and a steel gritrecycling machine 403, for example, to which dried steel grit isconveyed from the steel grit dryer is shown.

The steel grit dryer 400 includes a pre-classifier 404 with which thevacuum hose 402 that is used by an operator to vacuum up steel grit isin fluid communication. The pre-classifier 404 may include a rotating orrotary trommel, vibrating screen, or any other type of pre-classifierthat is configured to remove large objects, such as dead birds, shoes,or other debris, that are vacuumed into the steel grit dryer 400 via thevacuum hose 402. The steel grit dryer 400 a may include a first vacuumbreak 405 a that may be used to stop vacuum pressure airflow frompassing through the vacuum hose 402 beyond the vacuum break 405 a, and asecond vacuum break 405 b that may be used to stop vacuum pressureairflow from being pulled from the pre-classifier 404. The use of thevacuum break 405 a may be used in the event of an emergency or clog atthe vacuum hose inlet, such as an operator or debris being pulled intothe vacuum hose. In accordance with the principles provided herein, therotary trommel may be a double-drum trommel, including a conical-shapeddrum that rotates within a tubular-shaped drum, as further shown anddescribed in FIGS. 6A and 6B.

More particularly, the pre-classifier 404, if configured as a rotarytrommel, may be configured to perform several processes. A primaryprocess is to filter the incoming steel grit that is being recycled byremoving oversized material (e.g., larger than perforations defined by afirst rotating drum) in to a discharge end opposite the end in which thesteel grit enters the pre-classifier 404, as further providedhereinbelow. Another function is to allow both dry and/or wet and dampgrit materials to pass through the perforations defined by the sidewallof the first rotating drum optionally a second rotating drum and to fallvia conduit 406 that extends from the pre-classifier 404 to a lifter408. The conduit 406 allows steel grit to pass from the pre-classifier404 to the lifter 408 for continuing the grit processing using gravityas a primary conveyer in the ambient air pressure thereafter.

With regard to the oversized material being discharged by thepre-classifier 404, although not shown, the oversized material may fallinto a chute that remains under vacuum pressure during operation of thevacuum. The dryer may be configured with an air lock in the chute toenable the debris to be released during operation of the dryer 400. Inanother embodiment, and because the amount of oversized debris istypically limited, the chute may be configured with an air-tight doorand the operator may open the door when the steel grit dryer is not inoperation or when the vacuum is turned off. Alternative configurationsare possible to enable an operator to remove the oversized debris to beremoved from the dryer 400.

The lifter 408 may include any mechanism that enables the steel grit tobe lifted after being pre-classified. The lifter 408 may include anauger, conveyor, bucket elevator, pneumatics, hydraulics, and/or anyother mechanical, electromechanical, pneumatic, or other mechanism, forexample, to hoist the steel grit for further processing. In anembodiment, an auger that includes a screw with flights for conveyingthe steel grit at an angle, such as a 60° angle, may be utilized.

From the lifter 408, the steel grit to a higher elevation may be passedin a conduit 410 into an airlock 412. The airlock 412 may include arotary valve or any other airlock, such as a duel butterfly valve. Theairlock 412 allows for the steel grit to pass from a vacuum air pressureinto an ambient air pressure for further processing therein. It is notedthat in the event that the rotary airlock 412 positioned below thelifter 408 ever gets plugged, the availability of a manually opened andlocked emergency discharge door at the top of the lifter 408 (e.g.,rotary auger), positioned just below the opening to the rotary airlock412, is available to provide a way of cleaning out the lifter 408 in theevent that the lifter 408 get plugged. In an embodiment, however, thesystem may be configured to limit grit from filling the rotary airlock412 (e.g., 50% full), thereby protecting the integrity of the rotaryairlock 412, as further provided herein.

A conduit 414 may be in fluid communication with the airlock 412, and bearranged to guide the steel grit into a feeder 416 for delivery into adryer 420 in which the steel grit is to be dried. The feeder 416 may bea tube or any other conduit or manifold. In an embodiment, the feeder416 may be a chute or dropout box having a high angle so that the steelgrit, which is likely still moist when being vacuumed in wet conditions,does not stick to sidewalls of the feeder, but rather slidestherethrough.

A conduit 418 may extend from the feeder 416 into a dryer 420. Theconduit 418, which may be open (e.g., slide) or closed (e.g., pipe), maybe part of the feeder 416 or may be a connection member, such as a pipe,that directs the steel grit that passes through the feeder 416 into thedryer 420. In an embodiment, the dryer 420 may include a rotary drum(see FIGS.). Alternatively, the dryer may include a screen, such as amoving screen, on which the steel grit may be conveyed from a first endto a second end while being dried in heated air through which the screenpasses.

To heat the air, a heater 422 may be utilized. In an embodiment, theheater 422 includes a burner that produces a flame that directly orindirectly heats air in which the steel grit is to be dried within thedryer 420. Alternatively stated, because the steel grit does not absorbmoisture, water is evaporated by the heat within the dryer 420. In anembodiment, the heater 422 includes a heat exchanger that includes a boxwithin which a flame or other heating element may produce heat, andwalls of the box may radiate the heat therefrom. The use of a heatexchanger prevents “dirty air” (e.g., carbon emissions) produced by thefuel that creates the flame to contact the steel grit being dried.

Modulating Valve

To control temperature of the heated air within the dryer 420, amodulating or temperature control valve 424 may be utilized to removeexcess heat within a conduit 426 that conveys heated air produced by theheater 422 into the dryer 420. The modulating valve 424 may further bein fluid communication with an heat exhaust 428 via a conduit 430. In anembodiment, if the temperature of the heated air in the dryer 420 isdirectly (e.g., measured at the end of the rotating drum) or indirectly(e.g., measured in the conduit 426, measured by the temperature of thesteel grit exiting the dryer 420) measured to exceed a certaintemperature, then the modulating valve 424 may be (i) opened ortransitioned from a closed state to an open state, (ii) transitionedfrom a first open state to a second state (e.g., from a 20 degree angleto 40 degree angle or from a 60 percent open state to a 30 percent openstate or vice versa), or (iii) from an open state to a closed state toenable heat from the heater 422 to exit into the conduit 430 and out theheat exhaust 428 or be prevented from exiting from the heat exhaust 428.The modulating valve 424 may be a butterfly valve or any other valvetype that is capable of operating in high temperatures, such as 700° F.or otherwise that is produced by the heater 422. The conduit 430 may bealigned to be vertically higher than the conduit 426 so as to enable thehot air produced by the heater 422 to exit through the conduit 430 andout the heat exhaust 428 that may be disposed at or above a top of thesteel grit dryer 400. It should be understood that a variety ofdifferent configurations may be utilized to enable heated air producedby the burner 422 to exit out the heat exhaust 428 prior to entering thedryer 420 from the burner 422 to exit out the heat exhaust 428.

The modulating valve 424 may be controlled (e.g., using a proportionalcontroller) to open and close a certain percentage or angle. The anglemay control how much hot air is able to flow through the conduit 426 tothe dryer 420. The use of the modulating valve 424 may providing moreand/or faster control of heated air that enters the dryer 420 from theheater 422 than is possible by controlling temperature of the heater 422alone. In an embodiment, the heater 422 may be set to a steady stateheat output (e.g., 666K BTUs, 1M BTUs, 2M BTUs). However, as understoodin the art, many heaters have a maximum temperature change rate, so theuse of the modulating valve 424 generally provides more control thancontrolling temperature of the heater 422.

The configuration of the steel grit dryer 400 may enable the heated airfrom the heater 422 to flow into the dryer 420 when the modulating valve424 is in an open state, while the heated air may be prevented fromflowing into the dryer 420 when the modulating valve is in a closedstate. Because the modulating valve 424 may be controlled to be in anyamount (e.g., angle, percentage, etc.) when in the open state, theamount of heat that flows into the dryer 420 may be controlled.

To move air past the heater 422, especially in the case of using a heatexchanger, a fan 432 may be utilized to cause forced draft (FD) airflowto pass past the walls of the heater 422 via conduit 433 and move theheated air through the conduit 426 into the dryer 420 and/or conduit 430to be released by the heat exhaust 428 and the modulating valve 424 maybe varied to control how much heat passes into the dryer 420.Alternatively, the heater 422 may be varied along with the modulatingvalve 424. The fan 432 draws “clean” air (e.g., air external from thesteel grit dryer 400 or at least air not from within the heater 422) topush past the outside wall of the heater 422 to cause the heat to flowinto dryer 420. When pressure builds behind the modulating valve in theconduit 430, heat may be released by the heat exhaust 428. The pressuremay increase as a result of the modulating valve 424 being closed or inany open state in which the heat produced by the heater 422 builds inthe conduit 430. The fan 432 may operate at a constant rate or bealtered so as to increase the forced draft airflow to increase, whichmay cause more heat to be drawn from the walls of the heater 422. Theheat exhaust 428 may be a flapper valve or gravity damper that is set toopen in response to a certain pressure building within the conduit 430,which may be vertical similar to that of an exhaust stack of a truckwith a flapper valve disposed thereon.

Dust from the steel grit may be released as the steel grit is beingdried or rotated in the dryer 420. To remove the dust from the dryer420, the grit dryer machine 400 may include a fan 434 that generates aninduced draft airflow that pulls air through a conduit 436, dustcollector 438, conduit 440, and the dryer 420. The fan 434 may be largerthan the fan 432 as the amount of air that is drawn by the fan 434 ismore than the amount of air that the fan 432 is to push. For example, ifthe dryer 420 includes a 15 foot rotating drum, then the fan 434 may besufficient large to draws air through the entire or majority length ofthe drum.

In operation, which is further described in FIG. 4B, when the dryer 420is being operated in a grit dryer mode (i.e., to dry the steel grit),the air is heated to elevated temperatures (e.g., 100 degrees to 900degrees Fahrenheit), so a temperature of the air before and/or after theinlet and/or outlet of the dryer 420 may be measured and used to feedback to a controller (see FIG. 5) to control the modulating valve 424 inthe event that the heated air becomes too high. The temperature withinthe dryer 420 is generally at a lower temperature than the elevatedtemperatures generated by the heater 422, such as being between 100degrees and 700 degrees Fahrenheit along the length of the dryer 420. Itshould be understood that moisture in the steel grit causes thetemperature of the heated air to be lowered as a result of the moistureconsuming heat energy, while minimal or no moisture in the steel gritwill lead to the air temperature to be at a maximum or desired dryingtemperature. Similarly, temperature of the outside air at the locationof the steel grit dryer 400 may also play a role of the temperature ofthe air within the dryer 420. The dust collector 438 may have filtersthat have a maximum temperature to which the filters may be exposed. If,for example, the heated air coming from the dryer 420 is sensed to beabove a temperature threshold, then the controller may operate themodulating valve 424 to cause heated air to be released by the air vent428 via the conduit 430 so as to lower the heat of the air that is drawnfrom the dryer 420 and into the dust collector 438, thereby protectingthe filters from being exposed to too much heat and being damaged.

From the dryer 420, a conduit or manifold 442 may direct steel grit intoa dropout box 444. The conduit 442 may simply be air or may be a surfacedown which the steel grit may slide into the dropout box 444. Thedropout box 444 may be positioned above a re-entrainment valve 446 thatis positioned beneath a conduit 448 to control flow of steel grit thatexits the dropout box 444 prior to being re-entrained back into a vacuumhose 450 for delivery to a recycler via another vacuum hose 452 that maybe fluidly connected to the vacuum hose 450. The re-entrainment valve446 may be a pinch valve that squeezes to prevent and un-squeezes torelease steel grit from flowing through the conduit 448. Alternatively,the re-entrainment valve 446 may be a double or triple butterfly valve(operating as an airlock), slide valve, or any other valve that may beutilized to separate ambient air pressures from vacuum air pressures, asfurther described herein. From the pre-classifier 404, a heat processvacuum bypass path 454 in the form of a conduit (e.g., hose), forexample, may allow for vacuum pressure airflow to extend from thepre-classifier 404 to the vacuum hose 452 so as to avoid the heatprocess starting from the dryer 420. That is, heated air generated bythe heater 422 is prevented from entering the heat process vacuum bypasspath 454. It should be understood that the representation of the flowpaths including the various conduits, components, airflow paths, steelgrit flow paths is illustrative, and that the conduits, components,airflow paths, and steel grit flow paths may be varied, but provide thesame, equivalent, or similar function as provided herein. For example,the conduits may simply be interconnections or structural connectionsbetween structural components and/or modules, such as the feeder 416 andthe dryer 420.

Heat Process Vacuum Bypass Path

The vacuum pressure airflow may come from the vacuum hose 452 and begenerated by a vacuum device or vacuum on a steel grit recycling machineto which the steel grit dryer 400 is in fluid communication via thevacuum hose 452 or other form of conduit (e.g., manifold or duct of anymaterial). In an alternative embodiment, an independent or standalonevacuum that is not part of a steel grit recycling machine may beutilized to create the vacuum pressure airflow that extends to thevacuum hose 402 to enable a user to vacuum or pick up steel grit thatwas blasted onto a structure. The use of the heat process vacuum bypasspath 454 may allow a contractor that has a steel grit recycling machineto not have to purchase or rent a separate vacuum and also allow themanufacture of the steel grit dryer 400 not to have to include a vacuumon the vacuum machine, thereby saving cost and space on the steel gritdryer 400. The vacuum pressure airflow extends from the vacuum hose 452into the heat process vacuum bypass path 454, through the pre-classifier404, and into the vacuum hose 402.

Air Pressures

The steel grit dryer 400 may be configured to operate with variousin-vacuum and out-of-vacuum air pressure levels along with positive(forced draft), negative (induced draft), and neutral (no draft)airflows within each of the in-vacuum and out-of-vacuum air pressurelevels. As shown in FIG. 4, vacuum air pressure exists in the vacuumhose 402, vacuum bypass path 454, vacuum hoses 450 and 452,pre-classifier 404, lifter 408, and conduit 410. Ambient air pressureexists in the conduit 414, feeder 416, conduit 418, dryer 420, conduits433, 430, 426, conduits 440, dust collector 438, conduit 436, fans 434,442, dropout box 444, and conduit 448. More broadly, the vacuum pressureis separated from the ambient pressure by both the airlock 412 andre-entrainment valve 446 (i.e., between the airlock 412 andre-entrainment valve 446, ambient air pressure is maintained, and infront of the airlock 412 and behind the re-entrainment valve 446, thevacuum pressure is maintained).

Moreover, steel grit may flow along a heat process path and the vacuumpressure airflow may bypass the heat process path without steel gritprior to the dryer 420 and then the steel grit may be re-entrained intothe vacuum pressure airflow after the dryer 420 that pneumaticallycarries the steel grit to a steel grit recycler, for example. Moreparticularly, the vacuum hose 402 may include a vacuum pressure so as tobe capable of drawing steel grit therethrough. As the vacuum hose 402may be 1,000 feet or longer, the vacuum pressure airflow may besufficiently strong (e.g., 29 inHg or 0.98 Bar) so as to generate avacuum pressure airflow or vacuum airflow (e.g., greater than 100 mph).The vacuum pressure airflow may extend through the pre-classifier 404 soas to help the steel grit to enter the pre-classifier 404 along withdrawing large debris through a debris dropout end of the pre-classifier404. The vacuum pressure airflow may exit through the heat processvacuum bypass path 454 while leaving the steel grit to be furtherprocessed through the heat process path (e.g., between the airlock 412and the re-entrainment valve 446), as shown.

Despite the vacuum pressure airflow exiting through the bypass path 454,the vacuum pressure itself is maintained through the conduit 406, lifter408, and conduit 410 until the airlock 412, where the airlock 412maintains the vacuum air pressure on one side and ambient air pressureon the other side. That is, conduit 410 has a vacuum air pressure (e.g.,29 inHg) and conduit 414 has an ambient air pressure (e.g., 1 Atm). Theconduit 414 may have a slight negative pressure airflow so that air isdrawn through the conduit, feeder 416, and conduit 418. The slightnegative pressure airflow may be generated by the fan 432 that creates aforced draft airflow to the dryer 420 as well as the fan 434 thatgenerates an induced draft airflow through the conduit 436, dustcollector 438, conduit 440, and into the dryer 420. The induced airflowby the Fan 434 pulls dust released from the grit into the dust collector438. As previously described, the re-entrainment valve maintains theambient air pressure on the side of the dropout box 444 and vacuum airpressure on the side of the vacuum hose 450.

In operation, the re-entrainment valve 446 may be controlled toperiodically or aperiodically release dried steel grit into the vacuumairflow in the conduit 450. In controlling the re-entrainment valve 446,it may be desirable to allow sufficient steel grit to flow through thevalve such that vacuum pressure is maintained by the aperture defined bythe valve 446 by fully or being nearly fully filled by the steel gritthat is flowing through the aperture. That is, if the aperture is notfilled, the ambient air pressure in the conduit 448 and dropout box 444would transition to a vacuum air pressure, so having steel grit fill theaperture limits or prevents the vacuum pressure from crossing there-entrainment valve 446. Such a re-entrainment valve 446 mayalternatively be an airlock, but the use of a re-entrainment valve 446is generally considered to be more efficient for flowing materialsbetween different air pressures. Because the vacuum air pressure is somuch lower than ambient, the steel grit is drawn through there-entrainment valve 446 so control of the valve 446 helps in acontrolled manner to ensure that steel grit remains above the valve 446,thereby maintaining a “grit seal.” Hence, a sensor, timer, orcombination thereof may be used to help ensure that steel grit ismaintained within the conduit 448 and/or dropout box 444 while there-entrainment valve 446 is releasing the steel grit back into thevacuum air pressure airflow in the conduit 450 and/or vacuum hose 452.

It should be understood that while the configuration of the steel gritdryer 400 is that of an inline steel grit dryer, that the steel gritdryer may be configured to operate without being inline in that anonboard vacuum may be utilized such that the endpoint of the steel gritis within the steel grit dryer 400. Such a non-inline configuration ofthe steel grit dryer may accommodate for smaller steel grit blastoperations including those that use a steel grit blasting machine thatdoes not also include a recycler. In such a configuration, othercomponents, such as a steel grit separator (e.g., magnetic drum) may beincluded with the steel grit dryer components.

Steel Grit Dryer Electrical Control System

With specific regard to FIG. 4B, a schematic showing electricalcomponents for controlling the steel grit dryer 400 are shown.Particularly, a controller 454 that includes one or more computerprocessors may be in communication with components of the steel gritdryer 400. The controller 454 may execute software 455 that is used tomonitor the components and operation of the dryer 400, control operationof the components of the steel grit dryer 400, and/or communicateinformation to an operator or other computers for monitoring operationof the steel grit dryer 400. The components may include thepre-classifier 404, lifter 408, airlock 412, dryer 420, and otherelectrical, electromechanical, electro-pneumatic, electro-hydraulic,electro-optical, and other components for use in providing thefunctionality of the steel grit dryer 404. The controller 454 may bepositioned on a printed circuit board 456 with other electricalcomponents. The controller 454 may be in electrical communication withan input/output (I/O) device 458 for use in communicating withcomponents on the steel grit dryer 400 and a communications network (notshown), such as a wireless communications network, via an antenna 459,and memory 460 for use and storing software and data.

In an embodiment, the data may be communicated via a local wirelesscommunications network via the antenna 459 using a local wirelesscommunications protocol (e.g., WiFi®, Bluetooth®) or cellular networkusing a cellular communications protocol, as understood in the art. Itshould be understood that more than one antenna and communicationsprotocols may be available for wireless communications. In anembodiment, a local mobile device, such as an electronic device that canbe worn on a wrist or clothing, may be in direct communication with thecontroller 454 so as to enable an operator to control various functionsvia the electronic device. Such functions may include turning ON/OFF thegrit dryer, activating the vacuum break 405 a and/or 405 b in the eventof an emergency, adjusting speed and/or temperature of one or morecomponents of the steel grit dryer, changing a mode of the steel gritdryer (e.g., normal mode to a fast pass mode), and so on.

The controller 454 may be in communication with a sensor bus 462 forreceiving data signals from sensors disposed on the steel grit dryer400, as further described herein. The controller 454 may also be incommunication with a control bus 464, which enables the controller tosend and receive control signals 465 with the various components on thesteel grit dryer 400. It should be understood that the sensor bus 462and control bus 464 may be analog, digital, combination of analog anddigital, and may be an industry standard (e.g., CANN bus) or proprietarybus.

The controller 454 may also be in communication with a human-machineinterface (HMI) 466 to enable an operator to control the steel gritdryer 400, including setting up parameters and variables, performingdiagnostics, updating software, calibrating modules and sub modules,and/or performing any other functions in accordance with the principlesprovided herein. The HMI 466 may be a touch screen display, non-touchscreen display, remote controller, app executable on a mobile smartphoneor other mobile electronic device, or otherwise.

A weather station 468, which may include a variety of sensors that arecapable of measuring temperature, pressure, humidity, and any otherenvironmental conditions at the steel grid dryer 400, may be included onthe grit dryer 400 and in communication with the controller 454. Data470 from the weather station 468 may communicated with or be polled bythe controller 454. The data 470 may be used in adjusting or otherwisecorrelating parameters of the steel grit dryer 400. For example, thedata 470 from the weather station 468 may be correlated withtemperatures within the dryer 420 so that the heater 422 may be adjusteddepending upon the atmospheric temperatures, for example.

A number of sensors are disposed at or in the various components of thesteel grid dryer 400. For example, temperature sensors (T), pressuresensors (P), load cell (LC) sensors, level sensors (LS), speed sensors(S), inclinometer sensors (I_(x), I_(y)), and/or other sensors,including the sensors that are built into various components orequipment on the steel grit dryer 400. The temperature sensors (T) maybe used to measure temperature at various points in or at the dryer 400.

The pressure sensors (P) may be used to measure air and/or other fluidpressure of the dryer, including both in vacuum pressures andatmospheric or ambient pressures. The load cell (LC) sensors may beconfigured to measure weight, in this case weight of the grit in thepre-classifier (assuming the weight of the pre-classifier being empty issubtracted from the total weight with steel grit contained therein). Thelevel sensors (LS) may be configured to measure level of steel gritwithin the dropout box 444. One of the level sensors (LS) may be used tomeasure a high level of steel grit in the dropout box 444, and anotherof the level sensors (LS) may be used to measure a low level of steelgrit in the dropout box 444. If the level is high, then the controller454 may control operation of the re-entrainment valve 446 to transitionto an open state to release steel grit into the vacuum hose 452, whileif the level of the steel grit in the dropout box 444 is low, thecontroller 454 may control operation of the re-entrainment valve 446 totransition to a closed state, if in an open state, thereby causing steelgrit to be collected in the dropout box 444. The speed sensors (S) maybe used to monitor speed of various components, including fan speed,drum rotation speed, pre-classifier rotation speed, etc. Theinclinometer sensors (Ix, Iy) may be used to determine angle of themachine in both x and y axes, and may cause an interlock of the dryer400 in the event that the angles of both the x and y axes are not withinrespective operational angular ranges, as further provided in FIG. 16.

The sensors may make sensor measurements and communicate that data 472to the controller 454 via the sensor bus 462. As an example, the loadcell (LC) sensors may be used to measure the weight in thepre-classifier 404, and the controller may be configured to adjust thesystem (e.g., slow down or create a vacuum break) in the event that thepre-classifier 404 is filled based on the weight indicating that thepre-classifier is full or stop the lifter 408 based on the weightindicating that the pre-classifier 404 is empty. Other examples offunctional operations based on sensor data being measured is describedhereinbelow.

Machine Configuration and Ornamental Features

With regard to FIGS. 5A-5K, illustrations of an illustrative steel gritdryer 500 that utilize the principles of operation are shown. The dryer500 may include an exoframe 502 that provides a rigid body to which thecomponents of the dryer 500 are attached. The exoframe 502 allows forthe components to be connected in such a manner that the components aremaintained in position relative to one another. A vacuum hose 504 mayextend from the dryer 500. A trommel 506, which is part of apre-classifier, may be positioned at the front of the dryer 500, and bethe first component that steel grit encounters when vacuumed into thedryer 500. Beneath the pre-classifier is a trommel trash barrel 508 intowhich debris that is filtered by the pre-classifier may be dropped.

A hydraulic cooler 510 may be used to cool hydraulic fluid used on thedryer 500. A lifter, in this case a grit auger 512, may extend angularlyupwards from the trommel 506 so as to lift the steel grit that exits thetrommel 506. A heat exchanger 514 may be positioned alongside the auger512. A rotary drum 516 into which heated air from the heat exchanger maybe positioned beneath the top of the auger such that the steel grit maybe dropped into the drum 516 via a conduit or manifold. An exhaust orinduced draft fan 518 may be disposed above and/or alongside the rotarydrum and be used to draw dust from the drum 516 into a dust collector520. A dropout box 522 may be positioned beneath the end of the drum 516so as to catch steel grit that exits the drum 516. A grit re-entrainmentvalve 524, which enables dried steel grit, to exit from the dropout box522. A vacuum hose 526 that passes beneath the dropout box 522 andconnects to the grit re-entrainment valve 524 may extend to a steel gritrecycling or other machine. The steel grit dryer 500 has variousornamental features, such as the exoframe, rotary drum, auger, overalllook, etc., that are identifiable as a result of being configured insuch a manner.

Continuing, the

With regard to FIGS. 5B-5K, different angular views, including rightside, left side, rear, front, right front perspective, front leftperspective, rear left perspective, rear right perspective, top, andbottom view, respectively, of the steel grit dryer 500 are shown. Theornamental features may be seen throughout the different angles.

Exoframe

Continuing with FIGS. 5A-5K, the exoframe 502 may be configured as astrong structure that prevents twisting or racking of componentsrelative to one another that are attached to the exoframe 502 thatmounts to a trailer 503. The trailer includes the components, includinga pair of eyebeams (e.g., 10-inch eyebeams) onto which the exoframe 502may be supported via large springs. Typical mobile equipment use legsthat mount equipment to a floor of a trailer. Such leg mounts, however,allow for the components to move relative to one another, especially asthe trailer flexes. The exoframe 502 is a welded structure with angulartruss members, thereby strengthening the structure. The exoframe 502enables multiple levels of components to be mounted to a commonstructure, and because of the exoframe 502 being rigid (i.e., unable tobend) because of the steel structure being welded, each level (e.g.,upper and lower) is able to maintain relative position of the componentsattached to one another. In an embodiment, a sprint or other flexibleconnection between the trailer and exoframe 502 may allow for thecomponents to be independent of the exoframe 502. In an embodiment, theexoframe 502 may have lift or hoist eyes 528, such as four lift eyes,connected to the top of the exoframe 502, thereby allowing for theexoframe 502 and grit dryer 500 to be gross weight lifted by a crane orother lifting machine. The eyes 528 may be positioned such that thecenter-of-gravity (COG) of the grit dryer 500 is centrally balanced. Asshown, the exoframe 502 provides for a cantilevered configuration (i.e.,the components in front of the trailer such that the trommel 506 is ableto be supported without bending.

Other Features of the Mobile Steel Grit Dryer

The dryer 500 may further include a master control panel that isconfigure to provide telematics to an operator remotely located from thedryer 500. The control panel may include a human-machine interface(HMI), but also be configured to collect, process, and communicate datalocally and/or remotely to an operator, contractor, municipality, orotherwise. For example, the data may be communicated via acommunications network, such as a satellite communications network, sothat an operator may see information about the dryer (e.g., operationalor non-operation information) on a computer or mobile device.

The trailer 503 may be configured with screw jacks 532 that may bemanual or powered. There may be two or more screw jacks 532. In anembodiment, there are four screw jacks 532, one on each corner. If thescrew jacks 532 are powered, the screw jacks may be in communicationwith the controller such that an operator, such as a six-foot man 534,may control operation of the screw jacks 532 via the master controlpanel 530 or remotely via a remote control electronic device that is incommunication with the controller operating the dryer 500.

The dryer 500 may further include a solar panel 536 disposed on top ofthe exoframe 502 or elsewhere to charge a battery (not shown) on thedryer 500. The battery may be used to power the control panel 530, forexample, which may be configured to communicate location information ona periodic or aperiodic basis, even when the dryer is not being used.The dryer 500 may also include a diesel tank 538 for providing fuel to aburner within the heat exchanger 514 when drying steel grit. It shouldbe understood that the dryer 500 may be configured to use other fuelsources, such as gasoline or electricity.

Double Trommel

With regard to FIG. 6A, an illustration of an illustrativepre-classifier configured as a double drum trommel 600 a is shown. Thetrommel 600 a may include an external drum 602 and an internal drum 604that extends axially within the external drum 602. In an embodiment, theinternal drum 604 may be conical shaped with a small diameter end 606defining an opening that is used as an input into the drum 604 for steelgrit being recycled, and a large diameter end 608 that defines anopening for use as an output of the internal drum 604. Because theinternal drum 604 is conical, the drum 604 has a downward slope when thecentral axis of the drum 604 is horizontal. The internal drum 604 mayhave a sidewall that defines openings 605 along the entire or partiallength of the drum 604. The openings 605 may be small enough (e.g.,⅜-inches in length, width, or diameter, but may be slightly larger(e.g., ½-inches or smaller) to allow for the steel grit to pass throughthe openings 605 so as to fall into the external rotating drum 602.

Debris that is larger than the openings 605 may flow down the wall ofthe internal drum 604 and eventually pass out the large diameter, openend of the internal drum 604. That is, the large diameter end 608 of theinternal drum 604 may enable large debris (e.g., cans, dead birds,nails, etc.) that does not pass through the openings 605 of the internaldrum 604 into the tubular, external drum 602 to fall out the open end ofthe internal drum 604. The one or both of the ends of the internal drum604 may be vertically aligned with the end(s) of the external drum 602,thereby allowing the steel grit to enter into the internal drum 604 andlarge debris to exit out of the internal drum 604 without contacting theexternal drum 602. The external drum 602 may have a solid sidewallexcept for a series of openings 610 a and 610 b (collectively 610) thatare positioned closer to the end 608 such that steel grit that falls outof the openings 605 of the internal drum 604 into the external drum 602passes out the openings 610 of the external drum 602. It should beunderstood that alternative configurations of openings may be used. Inan embodiment, guides, flights, or other internal structure (see FIG.6B) of the external drum 602 may help guide the steel grit toward theopenings 610 such that the steel grit falls out of the openings 610 intoa drop box (see FIG. 4A) to be re-entrained back into the vacuumairflow, as previously described.

A conduit 612 may enable a steel grit vacuum airflow 614 to draw steelgrit upward through the conduit 612 and into walls 616 a and 616 b(collectively 616) that slow down the steel grit from speeds that mayreach upwards of over 100 mph to around 20 mph, thereby allowing for thesteel grit to fall out of the vacuum airflow and onto an internalsurface of the internal drum 604. The vacuum airflow may continue movingthrough the internal drum 604 from input end 606 to the output end 608to help draw lightweight and larger debris that does not pass throughthe openings 605 to be dropped out of the output opening of the internaldrum 604.

With regard to FIG. 6B, an illustration of a cutaway view of the doubledrum trommel 600 is shown. The internal drum 604 may have lifters 618that extend axially within the drum 604 to help lift and move the steelgrit along the inside surface of the drum 604. As further shown, theexternal drum 602 may have one or more helical guide(s) 620 that movesteel grit that exits from the internal drum 604 to the external drum602 towards the openings 610. It should be understood that the lifters618 and guide(s) 620 may have alternative configurations and provide forthe same or similar functionality. For example, flights or other shapedmembers that are connected to the internal surface of the drum(s) 602and 604 may be utilized. By using a solid portion of the external drum602 to the openings 610, steel grit that exits the internal drum 604 maybe moved to a position over a hopper with steep-angled sidewalls forloading into a lifter (see, for example, FIG. 5) so that the grit, whichmay be moist, does not stick to the sidewalls of the hopper when beingflowed to the lifter.

Load Cells

With regard to FIGS. 7A-7C (collectively FIG. 7), an illustration of anillustrative pre-classifier 700, such as the double drum trommel 600 ofFIG. 6, that utilizes one or more load cells to weigh steel grit withinthe pre-classifier 700 is shown. In order to weigh the pre-classifier700, the pre-classifier has to be able to move vertically as thepre-classifier 700 is filled and unfilled with steel grit. Thepre-classifier 700 may have such that the pre-classifier itself is notconnected to the exoframe bushings 702 a-702 d (collectively 702)connected thereto through which rods 704 may be extended. The rods 704may extend through openings of brackets 706 mounted to vertical posts708 of the exoframe (see FIG. 7B). A cap 710 may be mounted on the topof the rods 704. The vertical posts 708 may retain the pre-classifier700 in fixed positions along the x-axis and y-axis, while the brackets706, bushings 702, and rods 704 allow for the pre-classifier to movealong the z-axis.

As shown in FIG. 7C, the pre-classifier 700 is shown to be positioned onload cells 712 a and 712 b (collectively 712) positioned on surfaces 714a and 714 b and below bottom surfaces 716 a and 716 b of thepre-classifier 700. It should be understood that more or fewer loadcells may be utilized, but using at least two provides for redundancy ofmeasurement of weight of the pre-classifier.

As understood in the art, load cells are used to weigh objects. Largeload cells may be used to weigh heavy objects. As steel grit fills thepre-classifier 700, the load cells may sense that the weight of thepre-classifier 700 with the steel grit increases, and provide that datato a controller of the steel grit dryer for control of the grit dryer,as further described herein.

One problem with load cells is that the load cells 712 can be damagedduring transit of the mobile grit dryer 700. The reason for potentialdamage is that the load cells have very little movement (e.g., about ¼of an inch), so if the mobile grit dryer is transported over roughsurfaces with holes or otherwise, which is fairly typical in and aroundjobsites at which the steel grit dryer 700 is to be used. To protect theload cells 712 from damage, a pneumatically or other power sourcecontrolled piston 718 may be utilized to cause an arm 720 to drive a cam722. The cam 722 may be configured to rotate and cause thepre-classifier 700 to be move upwards to a fixed position that preventsthe pre-classifier to push down on the load cells 712, therebyminimizing or preventing the load cells 712 from being damaged duringtransport of the steel grit dryer on which the pre-classifier 700 ismounted.

To control and drive the piston 718, a pneumatic control line (see FIG.9) that directly or indirectly connects to the piston 718 may beconnected to a truck brake service and supply line. Along the controlline, a pneumatic switch that indicates that the control line isconnected to a truck supply line, thereby causing the piston 718 toengage so as to drive the cam 722 to a locked or mobile position thatremoves some or all of the weight of the pre-classifier from resting onthe load cells 712. If the control line is removed from the truck brakeservice and supply line, then the piston 718 may disengage so as tolower the pre-classifier 700 to be loaded back onto the load cells 712.

With regard to FIG. 8, a flow diagram of an illustrative process 800 formeasuring weight of steel grit within a pre-classifier of a mobile steelgrit dryer is shown. The process 800 may start at step 802, where motionof the pre-classifier disposed on one or more load cells to weigh thepre-classifier with steel grit that is contained in the pre-classifierover time is limited to vertical motions. The motion may be limited byfixedly attaching a bracket to an exoframe or other rigid member on atrailer or skid, for example, of the mobile steel grit dryer. A bushingor other component may be fixedly attached to the pre-classifier, and analignment member (e.g., rod) may be aligned with the bracket and bushingto enable the pre-classifier to move vertically relative to the exoframeor other rigid member, but not move horizontally relative to theexoframe or other rigid member. The process 800 may measure weight ofthe pre-classifier using the one or more load cells over time (i.e.,dynamically) at step 804. The measurement may be performed at thepre-classifier or a processor remotely located from the pre-classifierthat receives weight signals from the load cell(s). At step 806, one ormore functional operations of the steel grit dryer may be dynamicallymodified in response to determining that the weight of the steel grit inthe pre-classifier is above or below threshold values. The functionaloperations may include breaking a vacuum pressure to a vacuum hose,opening or closing a valve, stopping operation of one or morecomponents, communicating a notification to an operator, or otherwise.

With regard to FIG. 9, an illustration of a scene 900 in which a truck902 may be connected to a mobile steel grit dryer 904 to pull the mobilesteel grit dryer to a jobsite, for example, is shown. The truck may havea truck brake service and supply line 906, which typically has twoports, one for providing air for use by air brakes and one for control.A control line 908 may be connected to the line 906 for receiving air. Apneumatic switch 910, which may be located along the control line or onthe dryer 904, may be configured to cause a lift mechanism 912, such asa piston or other solenoid to active and deactivate in response to theservice and supply line 906 being activated. For example, if thepneumatic switch 910 detects that the control line is connected to thesupply line 906, then the lift mechanism may cause a pre-classifier 914to be lifted, mechanically, electrically, pneumatically, or otherwise,so that force of the pre-classifier is not entirely on load cell(s)positioned to weigh the pre-classifier 914. When the control line 908 isnot connected to the line 906 or the line 906 is deactivated, the liftmechanism 912 may be deactivated so that the pre-classifier is restingwith its full weight on the load cell(s).

Planetary Gear Box

Rotating drums are often supported by rollers. Because most rotatingdrums used for drying material, such as grit, dirt, or grains, are notpositioned on mobile equipment, the use of rollers provides sufficientstability for the rotating drums. However, for a mobile steel gritdryer, the drum in which the steel grit is to be dried has to be moresecure than simply being positioned on rollers. The drum may be 15 feetor longer and weigh several thousand pounds, so security fortransporting the rotating drum is necessary to avoid the drum fromfalling off a trailer or skid when being transported between jobsites.

With regard to FIGS. 10A-10C, illustrations at different angles and zoomlevels of a steel grit dryer 1000 a, 1000 b, and 1000 c, respectively(collectively 1000), of a rotating drum 1002 in which steel grit may bedried is fixedly directly or indirectly secured to a structure 1004,such an exoframe, at which the rotating drum is positioned is shown. Tosecure the rotating drum 1002 to the structure 1004, a three-pointmounting system may be utilized. The three-point mounting system mayinclude a planetary gear box 1006 at a first end of the rotating drum1002 and a pair of trunnion rollers 1008 a/b (collectively 1008)disposed beneath a second end (or at least towards the second end) therotating drum 1002. The rollers 1008 may be motorized or free to rotate,while the planetary gear box may drive rotation of the drum 1002. Tosecure the planetary gear box 1006, a mount 1010, such as an I-beam, maybe fixedly mounted by welding to the exoframe 1004. The mass andstrength of the I-beam is sufficiently strong that the drum 1002 isprotected from falling off the three-point mounting system duringtransport. As shown, a dropout box 1012 is positioned prior to theplanetary gear box 1006 so as to enable the drum 1002 to drop driedsteel grit via the dropout box 1012 via openings defined by the wall ofthe drum 1002, as previously described.

With regard to FIGS. 10B and 10C, the drum 1002 is shown to be extendingthrough the dropout box 1012. A flange 1014 may be welded to the end ofthe drum so as to seal the end to prevent steel grit from falling outthe end. A connector 1018 that may include one or more components, suchas an endplate to prevent steel grit from exiting the drum 1002 andconfigured to be connected via bolts to the flange 1014, and mountingplate 1020 that may be configured to be bolted to a mounting plat on theplanetary gear box 1006. It should be understood that alternativeconfigurations may be utilized to secure the drum 1002 to the planetarygear box 1006 and provide the same or similar function.

Vacuum Bypass Process

With regard to FIG. 11, a flow diagram of an illustrative process 1100for drying steel grit is shown. The process 1100 may start by receivinga vacuum pressure airflow by a heat process bypass path of a steel gritdryer. In receiving the vacuum pressure airflow, the heat process bypasspath may receive the vacuum pressure from a vacuum disposed on a steelgrit recycling machine. The vacuum may alternatively be on a steel gritblast machine. Still yet, the vacuum may be a standalone vacuum. Thebypass path travels past the heating process such that no heated airgenerated by a heater enters the heat process bypass path. The bypasspath may include a conduit, such as a hose or more rigid structure thatextends between the pre-classifier and dropout box at the exit of thedryer (e.g., rotating drum within which heated air is used to dry thesteel grit). At step 1104, the vacuum pressure airflow may be appliedfrom the heat process bypass path to a vacuum hose extending from thesteel grit dryer used to vacuum the steel grit into the steel grit dryerafter being blasted against a structure and prior to being processed bya steel grit blast machine. In other words, the vacuum pressure airflowmay travel around the heating process used to dry the steel grit. Atstep 1106, the steel grit may be transitioned from the vacuum pressureairflow prior to drying the steel grit. The transition process mayinclude using an airlock. At step 1108, the steel grit vacuumed into thesteel grit dryer may be dried to produce dried steel grit. At step 1110,the dried steel grit may be re-entrained back into the vacuum pressureairflow after the heat process bypass path to cause the dried steel gritto be vacuumed from the steel grit dryer. In an embodiment, the driedsteel grit may be vacuumed to a steel grit recycling machine at whichthe vacuum may be operating.

Modulating Valve

With regard to FIG. 12, a flow diagram of an illustrative process 1200of operating a modulating valve for use controlling temperature used todry steel grit is shown. The process 1200 may start at step 1202, whereheat from a heat source may be generated to heat air in which the steelgrit is to be dried. The heated air may be caused to flow through afirst conduit toward a steel grit drying region in which the steel gritis to be dried at step 1204. At step 1206, in response to measuring thatthe heated air exceeds a predetermined temperature value, the heated airmay be released from the first conduit prior to the heated air enteringthe steel grit drying region so as to control temperature of the heatedair within the steel grit drying region. At step 1208, the steel gritmay be dried in the steel grit drying region. In an embodiment, thesteel grit drying region may be a rotating drum.

Fast Pass

With regard with FIG. 13, a flow diagram for a process 1300 foroperating a steel grit dryer in different modes is shown. The process1300 may start at step 1302, where a determination may be made as towhether to operate the grit dryer in a first mode or a second mode. Itthe determination is made at step 1302 to operate the steel grit dryerin the first mode, then the process 1300 continues to step 1304, wherethe steel grit dryer is operated in the first mode to dry steel gritwith first settings. It the determination is made at step 1302 tooperate the steel grit dryer in the second mode, then the process 1300continues to step 1306, where the steel grit dryer is operated in thesecond mode with different settings than the first mode. The firstsettings may be to dry the steel grit at a certain temperature and movethe grit at a certain speed. The second settings may be to dry the steelgrit at the same or different temperature and move the grit at adifferent speed. Alternatively, the second settings may be to not drythe steel grit, but rather remove dust from the steel grit. Other modesand/or settings are possible.

Pre-Classifying Using a Double Trommel

With regard to FIG. 14, a flow diagram of an illustrative process 1400for pre-classifying steel grit is shown. The process 1400 may start atstep 1402, where a vacuum pressure airflow into a first end of a firstrotating drum disposed inside a second rotating drum may be generated.At step 1404, the steel grit may be filtered through perforationsdefined by the first rotating drum such that the steel grit falls intothe second rotating drum. At step 1406, debris larger than theperforations may be released out of a second end of the first rotatingdrum. In releasing the larger debris, the larger debris may be droppedinto a chute for later removal. In an embodiment, the removal may bemade after removing a vacuum pressure in the pre-classifier (e.g., atrommel). At step 1408, the steel grit may be axially propagated withinthe second rotating drum. At step 1410, the steel grit may be dropped orotherwise removed from the second rotating drum for further processing.

Manufacturing a Mobile Steel Grit Dryer with an Exoframe

With regard to FIG. 15, a flow diagram of an illustrative process 1500for manufacturing a mobile steel grit dryer with an exoframe is shown.The process 1500 may start at step 1502, where an exoframe is directlyor indirectly coupled to a mobile trailer. At step 1504, componentsconfigured to pre-classify and dry steel grit vacuumed into the mobilesteel grit dryer may be connected to the exoframe.

Angle Sense Interlock

In order for any of the mobile steel grit dryers described herein, suchas the mobile steel grit dryer shown in FIG. 5A, to operate properly, acertain angle is to be maintained for the rotary drum, trommel, andpossibly other components of the grit dryer. The angles include x andangles along the x and y axes. With further reference to FIG. 4B, tomeasure the angles of the steel grit dryer, inclinometer sensors (I_(x),I_(y)), and/or other sensor types may be utilized. The controller 454may be configured to restrict the steel grit dryer from operating in theevent that the angles are not within acceptable ranges. For example, therotary drum may have a transverse angle Ix may be within a range of 0degrees+/−1 degree, and the longitudinal angle Iy may be within a rangeof −2 degree to −3 degrees. It should be understood, however, that loweror higher angles may also work, such as −0.5 degrees to −5 degrees. Thecontroller 454 may be configured to notify an operator via the HMI 466or communication to a wireless device prior to being started that theangle(s) of the dryer 400 are not correct and prevent startup. Thecontroller may further be configured to continuously monitor theinclinometer sensors (I_(x), I_(y)) during operation of the machine andimmediately shut the grit dryer down in the event that the angle of thesteel grit dryer falls outside either of the angular ranges. In anembodiment, a notification may be provided to the operator as a warningshould the angle determine to change during operation.

To assist the operator with setting the dryer in the proper alignmentfor operation, the controller 454 may be configured to drive jacks orlanding gear 532 (or outriggers, if configured) that may be hydraulic,mechanical, and/or electromechanical. A controller in the control panel530 or elsewhere may be configured to monitor the angle. If the jacks532 are manual, then the control panel 530 may generate a tone orcommunicate a message to a mobile device of an operator to enable theoperator to more easily set the height of each of the jacks 532 to bringthe grit dryer 500 into compliance. In an embodiment, the controller ofthe control panel 530 may be configured to automatically set the properangular level of the trailer 503 so that the transverse and longitudinalangles are within specification for the mobile steel grit dryer tooperate (i.e., not be locked out by the controller measuring the anglesof the dryer 500). In being automatic, the controller may measure theangles transverse and longitudinal angles and automatically raise orlower the screw jacks 532 until the angles are within the proper ranges,as provided herein. In an embodiment, if it is determines that an angleis outside an acceptable angular range, the controller may be configuredto shut down one or more functions of the steel grit dryer,automatically drive the screw jack(s) 532 to correct the angle, and thenenable the one or more functions to be available again.

With regard to FIG. 16, a flow diagram of an illustrative process 1600for performing an angle sense interlock is shown. The process 1600 maystart at step 1602, where an angle of the mobile steel grit dryer may bemeasured. At step 1604, in response to determining that the angle isoutside of an angular range, the steel grit dryer may be prevented fromoperating. In being prevented, one or more functions or features may bedisabled either immediately or ramped down. Once the angle is back incompliance, a controller performing the process may enable the dryer (orthe one or more disabled features or functions) to operate again.

Wearable Device

For operators of any sort of large industrial vacuum system, the end ofthe vacuum hose where recovery takes place is often a substantialdistance from the vacuum producing system. This distance can be hundredsto even a thousand or more feet of separation. To achieve efficientvacuum production measured in pounds or tons of material per hour, thevacuum laborer at the end of the hose maintains an optimized balance ofair flow and negative static pressure to move the material beingrecovered by vacuum. This efficiency comes down to maintaining enoughair flow, defined by cubic feet of air per minute, velocity of theairflow and static pressure of the air flow. Vacuum laborers holding andguiding the hose learn by trial and error what combination delivers thebest balance of material recovery, but the level of proficiency gainedis unpredictable. This is typically done without the aid of any gaugesor meters to show the actual airflow velocity, volume of air or negativestatic pressure (vacuum). Yet on the vacuum producingmachine/pump/positive displacement blower, hundreds or thousands of feetaway, there is likely a negative pressure gauge that shows the level ofnegative pressure as it goes up and down based on the material beingvacuumed.

There are also other important valves, specifically the vacuum breakvalves on the grit dryer, that can be automatically controlled by thegrit dryer. These valves can be activated automatically to stop gritflow and/or air and grit flow into and out of the first component, therotary vacuum pre-classifier that uses a trommel screen to removeoversized materials as they are vacuuming into the unit. The automaticcontrol of these valves is driven by the levels of grit in the trommelhopper, along with a wide variety of other operating or problemconditions as the grit dryer or recycling machine operates.

The problems relate to the vacuum hose operator knowing or not knowingwhat is happening at the grit recycling machine, in addition to theoperators of those machines not knowing what is happening at the end ofthe hose where the vacuuming is taking place.

When a controlling event occurs at the recycling machine or grit dryingmachine, such as the vacuum air flow being turned ON or OFF, it cancause safety issues with the operators of the vacuum where material isbeing recovered. For instance, if the hopper level in the grit dryer orrecycler receiving hopper drops, the vacuum break will automaticallyclose and restore powerful vacuum airflows to the vacuum line. If thisoccurs without warning to the vacuum operators, given the power of theair flow, they can be injured if this catches them with the hose closeto their arms, legs or clothing. When the full vacuum force by air flowis restarted, the hose can attach itself to clothing and be very hard toremove.

It is also possible that an operator will want to change the speed, heatsetting or some other variable on the grit dryer as they move from wet,to damp to dry grit. It should be understand that the vacuum hoseoperators cannot sometimes see or even hear the vacuum producer on arecycler or grit dryer as they complete their work. So they areeffectively “blind and deaf” to the machine that makes it possible forthem to recover material by vacuuming. Their isolation from any visualor audible information complicates their process and eliminates theirability to control it in any way to increase productivity.

To improve operations for operators, the solution to the problems may betwofold.

First, provide the vacuum hose operator with information about theoperational status of the recycling machine and/or grit dryer. This willallow them to control the process of material recovery by vacuum in away that is safe and efficient. Having a method to show the vacuum hoseoperators what the level of vacuum is in inches of mercury or inches ofwater column at the pump that is creating the vacuum air flow. The PDblower, fan or turbine could be as much as several thousand feet awayfrom where the material is being vacuumed up. To optimize the smoothflow of material being vacuumed, it is necessary to keep a steadyairflow moving through the vacuum line by metering the material beingvacuumed into the hose. If this is not done, it is easy to vacuum toomuch material, which then overloads the vacuum line and stops the flowof air and vacuumed material. If too little is vacuumed, the productionvolume will be reduced.

The simplest comparison is to the advantage one gains by having aspeedometer on a car. With guidance from that instrument, it becomeseasy for anyone to drive a car at the legal speed. Second, by giving thevacuum hose operators control over vacuum break valves, grit dryingspeed and heat settings allows them to control the process in a way thatcan optimize productivity.

Features—Productivity gain

The gain that comes from having the bracelet indicate for instance thegreen color is that a vacuum laborer can be instructed by the color tocontinue at the same rate until the color might change to yellow,indicating the vacuum level had dropped into a caution zone. Should thelight change to red, it indicates the selected vacuum level will haverisen to a point where airflow is too low to optimize vacuumingproduction. It would be evident to the operator that they need to vacuumless material to increase the airflow but not so much that the yellowand then red indicators light on the other side of green.

If the vacuum level is kept in the green range, a steady, consistent andappropriate airflow will increase the tonnage of material that can bemoved per hour. Over an entire day of work, the increased production andlack of vacuum plugging will allow workers to vacuum many more pounds ortons of material per minute, hour and day.

Indication for Open Vacuum Break Valve

An additional light and/or sound would indicate that a vacuum breakvalve on the vacuum system is open, preventing any airflow. This willsometimes occur when the receiving hopper reaches a point of beingfilled to capacity, at which point it opens, bleeding off all vacuumairflow to the hose, preventing any vacuum recovery from adding morematerial to the receiving hopper.

Knowing when the vacuum break valve is open or closed is importantbecause when the valve finally closes again, the vacuum airflow willstart without warning. Should a worker put their hand over the end ofthe hose to test for airflow at this time, their hand could be broken bythe sudden vacuum created at the end of the hose.

The feature may include an industrial duty bracelet, that a worker wearson their arm, with three colors of lights. red, yellow and green. Theyindication of those lights would be calibrated to illuminate the greenlight when a selected vacuum level is reached. If the vacuum level goesabove that, in a calibrated range, the yellow light comes on. If thevacuum level goes even higher, the red light would be calibrated toilluminate, indicating that vacuum was too high. When the vacuum levelis too high, the air flow is reduced, which in turn reduces the amountof material being vacuumed. In a worst case scenario, the vacuum levelis driven high to a point where a high volume of waste material isvacuumed into the hose, which then caused a drop in airflow, furthercausing a plug of material in the hose that could be substantial. Theonly way this plug is removed, is to hold the vacuum at a high leveland/or dump out some of the waste material so that the airflow can berestored.

These signals can also be augmented by audible, visual and otherbiometric feedbacks to the operator. FIGS. 17A and 17B provideillustrative wearable devices that an operator may use to aid in thefeedbacks.

Features

A connection to the recycler and/or grit dryer that provides the vacuumoperator with data, in a variety of forms, to a device they are wearing,holding or observing.

A connection to the recycler and/or grit dryer that provides the vacuumoperator with the ability to control selected aspects of the vacuumproducer.

Structure—Hardware, Software

Hardware—Could take the form of a bracelet made of steel, plastic,rubber or other material that attaches to overalls by a positivesecuring method such as a wristband, waistband, badge or other form tomount on the human operator. On this is mounted an analog or digitalgauge, multicolor LED lights or other display device. Within iscontained a battery to power the device.

Function—Sensing, Communicating

Sensing signals sent to it via WIFI or other transmission medium. Thiscould include vacuum level in Hg, condition (open or closed) vacuumbreak valves.

Displaying data in the form of numerical or other data on the screen.Vacuum level in Hg shown graphically.

Adjustability of where the lights are calibrated to in Hg, allowingoperator to adjust that level to find the optimum vacuum level setting.

Steel Grit Moisture Measurement Tool with Digital Timer and VariableInterchangeable Orifices to Detect Moisture Level

Problem

With the advent of portable steel grit dryers, there is a need bycontractors for a simple, easy to use, effective method to determine themoisture content and/or flowability of steel grit particles. Because itwill be used on jobsites, in the field, to be effective, it may besimple to use, durable and accurate in measuring the relative moisturecontent and/or flowability.

Solution

As shown in FIG. 18, the solution may include a scoop tube, round orsquare, that allows it to easily be filled with grit, leveled off byhand, and then run through the test orifice using an electronic timingdevice to count down the time it takes to empty the grit through anorifice hole on the bottom. The time it takes to complete this would becompared to a chart of “grit viscosity” that would be correlated tomoisture level and the determination of whether it is beneficial to drythe grit or not.

The timing of this could be manual, using start stop buttons like astopwatch, on a digital timer, or automatic using proximity and opticalsensors.

Features

A manual scoop tube, round or square, that can be filled, then turnedsideways, allowing the grit to run out and through the testing apparatuswith variable orifices. A digital timer would activate when the scoop isturned to dump the grit into the calibrated orifice. This could also beconfigured in a way that allows the measuring container to then bedumped into the holding container. When completed, the measuring cup canbe inserted into the container hopper to reduce the size of the overalltool.

The timer can either be actuated manually or by an inclinometer thatsenses the tipping or by some other means.

Variable and bolt on orifice plates with differing hole sizes can beused to change the size of the hole used to measure the flowability ofthe grit and/or moisture content. The connection between a hole size andmoisture content/flowability will be determined by testing.

This device can fabricated from weldable materials, steel, aluminum andothers, or made out of injection molded plastic.

In normal usage, a person would hold the feed hopper in their left hand,scoop up grit into the measuring cup with the right hand, level off thegrit, place the feed hopper on top of the measuring cup, and flip itover. If on automatic, the flip of the feed hopper would initiatetiming. Or it could be done manually with start and stop buttons on thedigital timer, attached to the side of the feed hopper.

Additional Features

-   -   a. One hand scoop    -   b. Digital timer, automatically activated when grit is dumped        into measurement chamber    -   c. Variable orifice plates allow testing for different levels of        moisture

Structure—Hardware, Software

-   -   a. Scoop    -   b. Digital timer    -   c. Orifice plates

Function—Sensing, Communicating

-   -   a. Measuring volume    -   b. Timing of emptying

Selection of Orifice for Timing

The foregoing method descriptions and the process flow diagrams areprovided merely as illustrative examples and are not intended to requireor imply that the steps of the various embodiments must be performed inthe order presented. As will be appreciated by one of skill in the art,the steps in the foregoing embodiments may be performed in any order.Words such as “then,” “next,” etc. are not intended to limit the orderof the steps; these words are simply used to guide the reader throughthe description of the methods. Although process flow diagrams maydescribe the operations as a sequential process, many of the operationsmay be performed in parallel or concurrently. In addition, the order ofthe operations may be re-arranged. A process may correspond to a method,a function, a procedure, a subroutine, a subprogram, etc. When a processcorresponds to a function, its termination may correspond to a return ofthe function to the calling function or the main function.

The various illustrative logical blocks, modules, circuits, andalgorithm steps described in connection with the embodiments disclosedhere may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and steps have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentinvention.

Embodiments implemented in computer software may be implemented insoftware, firmware, middleware, microcode, hardware descriptionlanguages, or any combination thereof. A code segment ormachine-executable instructions may represent a procedure, a function, asubprogram, a program, a routine, a subroutine, a module, a softwarepackage, a class, or any combination of instructions, data structures,or program statements. A code segment may be coupled to and/or incommunication with another code segment or a hardware circuit by passingand/or receiving information, data, arguments, parameters, or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted via any suitable means including memorysharing, message passing, token passing, network transmission, etc.

The actual software code or specialized control hardware used toimplement these systems and methods is not limiting of the invention.Thus, the operation and behavior of the systems and methods weredescribed without reference to the specific software code beingunderstood that software and control hardware can be designed toimplement the systems and methods based on the description here.

When implemented in software, the functions may be stored as one or moreinstructions or code on a non-transitory computer-readable orprocessor-readable storage medium. The steps of a method or algorithmdisclosed here may be embodied in a processor-executable software modulewhich may reside on a computer-readable or processor-readable storagemedium. A non-transitory computer-readable or processor-readable mediaincludes both computer storage media and tangible storage media thatfacilitate transfer of a computer program from one place to another. Anon-transitory processor-readable storage media may be any availablemedia that may be accessed by a computer. By way of example, and notlimitation, such non-transitory processor-readable media may compriseRAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other tangible storagemedium that may be used to store desired program code in the form ofinstructions or data structures and that may be accessed by a computeror processor. Disk and disc, as used here, include compact disc (CD),laser disc, optical disc, digital versatile disc (DVD), floppy disk, andBlu-ray disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers. Combinations of the aboveshould also be included within the scope of computer-readable media.Additionally, the operations of a method or algorithm may reside as oneor any combination or set of codes and/or instructions on anon-transitory processor-readable medium and/or computer-readablemedium, which may be incorporated into a computer program product.

The previous description is of a preferred embodiment for implementingthe invention, and the scope of the invention should not necessarily belimited by this description. The scope of the present invention isinstead defined by the following claims.

1. A method of processing steel grit being used to treat a structure,said method comprising: receiving a vacuum pressure airflow at a heatprocess bypass path of a steel grit dryer; applying the vacuum pressureairflow from the heat process bypass path to a vacuum hose extendingfrom the steel grit dryer used to vacuum the steel grit into the steelgrit dryer after the steel grit has been blasted against the structureand prior to being reused by a steel grit blast machine; transitioningthe steel grit from the vacuum pressure airflow prior to drying thesteel grit; drying the steel grit vacuumed into the steel grit dryer toproduce dried steel grit; bypassing the vacuum pressure airflow pastheated air in which the steel grit is being dried; and re-entraining thedried steel grit back into the vacuum pressure airflow to cause thedried steel grit to be vacuumed from the steel grit dryer.
 2. The methodaccording to claim 1, further comprising re-entraining the dried steelgrit back into the vacuum pressure airflow on an opposite side of a heatsource relative to where the steel grit was transitioned from the vacuumpressure to the ambient pressure.
 3. The method according to claim 2,wherein re-entraining includes gravitationally releasing the dried steelgrit back into the vacuum pressure using the steel grit during there-entrainment to operate as a barrier to separate the ambient pressureand vacuum pressure.
 4. The method according to claim 1, furthercomprising drawing the vacuum pressure airflow through a pre-classifierthat includes a rotating drum having perforations defined by therotating drum to enable the steel grit to pass therethrough, therotating drum including an inlet port on a first end through which thesteel grit enters and an outlet port on a second end through whichdebris larger than the perforations, the vacuum pressure airflowentering through the inlet port and exiting the outlet port.
 5. Themethod according to claim 1, wherein receiving a vacuum pressure airflowincludes receiving a vacuum pressure airflow created by a steel gritblast machine via a conduit extending between the steel grit blastmachine and the steel grit dryer.
 6. The method according to claim 1,further comprising applying a pushed airflow within the steel grit dryerafter the steel grit is removed from the vacuum pressure to cause aclean airflow to draw heat from a heat source, the heated air caused bythe heat source being used to draw the steel grit.
 7. The methodaccording to claim 6, further comprising collecting dust from the steelgrit by a dust collector at the steel grit dryer by using an inducedairflow to pull the dust to the dust collector.
 8. The method accordingto claim 1, further comprising controlling a valve to release heated airprior to the heated air being applied to the steel grit, whereincontrolling the valve causes temperature of the heated air being appliedto the steel grit to be maintained at a desired temperature.
 9. Themethod according to claim 8, further comprising causing a vacuumpressure to be released in response to a user communicating a wirelesssignal to the steel grit dryer. 10-94. (canceled)